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java.lang.Object java.util.AbstractCollection<E> com.google.common.collect.TreeMultiset<E>
@GwtCompatible(emulated=true) public final class TreeMultiset<E>
A multiset which maintains the ordering of its elements, according to either
their natural order or an explicit Comparator
. In all cases, this
implementation uses Comparable.compareTo(T)
or Comparator.compare(T, T)
instead of Object.equals(java.lang.Object)
to determine
equivalence of instances.
Warning: The comparison must be consistent with equals as
explained by the Comparable
class specification. Otherwise, the
resulting multiset will violate the Collection
contract,
which is specified in terms of Object.equals(java.lang.Object)
.
Nested Class Summary |
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Nested classes/interfaces inherited from interface com.google.common.collect.Multiset |
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Multiset.Entry<E> |
Method Summary | ||
---|---|---|
boolean |
add(E element)
Adds a single occurrence of the specified element to this multiset. |
|
int |
add(E element,
int occurrences)
Adds a number of occurrences of an element to this multiset. |
|
boolean |
addAll(Collection<? extends E> elementsToAdd)
|
|
void |
clear()
|
|
Comparator<? super E> |
comparator()
Returns the comparator associated with this multiset. |
|
boolean |
contains(Object element)
Determines whether this multiset contains the specified element. |
|
int |
count(Object element)
Returns the number of occurrences of an element in this multiset (the count of the element). |
|
static
|
create()
Creates a new, empty multiset, sorted according to the elements' natural order. |
|
static
|
create(Comparator<? super E> comparator)
Creates a new, empty multiset, sorted according to the specified comparator. |
|
static
|
create(Iterable<? extends E> elements)
Creates an empty multiset containing the given initial elements, sorted according to the elements' natural order. |
|
SortedSet<E> |
elementSet()
Returns the set of distinct elements contained in this multiset. |
|
Set<Multiset.Entry<E>> |
entrySet()
Returns a view of the contents of this multiset, grouped into Multiset.Entry instances, each providing an element of the multiset and
the count of that element. |
|
boolean |
equals(Object object)
Compares the specified object with this multiset for equality. |
|
int |
hashCode()
Returns the hash code for this multiset. |
|
boolean |
isEmpty()
|
|
Iterator<E> |
iterator()
Returns an iterator over the elements contained in this collection. |
|
boolean |
remove(Object element)
Removes a single occurrence of the specified element from this multiset, if present. |
|
int |
remove(Object element,
int occurrences)
Removes a number of occurrences of the specified element from this multiset. |
|
boolean |
removeAll(Collection<?> elementsToRemove)
|
|
boolean |
retainAll(Collection<?> elementsToRetain)
|
|
int |
setCount(E element,
int count)
Adds or removes the necessary occurrences of an element such that the element attains the desired count. |
|
boolean |
setCount(E element,
int oldCount,
int newCount)
Conditionally sets the count of an element to a new value, as described in Multiset.setCount(Object, int) , provided that the element has the expected
current count. |
|
int |
size()
|
|
String |
toString()
|
Methods inherited from class java.util.AbstractCollection |
---|
containsAll, toArray, toArray |
Methods inherited from class java.lang.Object |
---|
clone, finalize, getClass, notify, notifyAll, wait, wait, wait |
Methods inherited from interface com.google.common.collect.Multiset |
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containsAll |
Methods inherited from interface java.util.Collection |
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toArray, toArray |
Method Detail |
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public static <E extends Comparable> TreeMultiset<E> create()
Comparable
interface. Furthermore, all such elements must be
mutually comparable: e1.compareTo(e2)
must not throw a
ClassCastException
for any elements e1
and e2
in
the multiset. If the user attempts to add an element to the multiset that
violates this constraint (for example, the user attempts to add a string
element to a set whose elements are integers), the add(Object)
call will throw a ClassCastException
.
The type specification is <E extends Comparable>
, instead of the
more specific <E extends Comparable<? super E>>
, to support
classes defined without generics.
public static <E> TreeMultiset<E> create(@Nullable Comparator<? super E> comparator)
comparator.compare(e1,
e2)
must not throw a ClassCastException
for any elements e1
and e2
in the multiset. If the user attempts to add an element
to the multiset that violates this constraint, the add(Object)
call
will throw a ClassCastException
.
comparator
- the comparator that will be used to sort this multiset. A
null value indicates that the elements' natural ordering should
be used.public Iterator<E> iterator()
iterator
in interface Multiset<E>
iterator
in interface Iterable<E>
iterator
in interface Collection<E>
public static <E extends Comparable> TreeMultiset<E> create(Iterable<? extends E> elements)
This implementation is highly efficient when elements
is itself
a Multiset
.
The type specification is <E extends Comparable>
, instead of the
more specific <E extends Comparable<? super E>>
, to support
classes defined without generics.
public Comparator<? super E> comparator()
public SortedSet<E> elementSet()
If the element set supports any removal operations, these necessarily cause all occurrences of the removed element(s) to be removed from the multiset. Implementations are not expected to support the add operations, although this is possible.
A common use for the element set is to find the number of distinct
elements in the multiset: elementSet().size()
.
In TreeMultiset
, the return type of this method is narrowed
from Set
to SortedSet
.
elementSet
in interface Multiset<E>
public int count(@Nullable Object element)
Multiset
Object.equals(java.lang.Object)
-based
multiset, this gives the same result as Collections.frequency(java.util.Collection>, java.lang.Object)
(which would presumably perform more poorly).
Note: the utility method Iterables.frequency(java.lang.Iterable>, java.lang.Object)
generalizes
this operation; it correctly delegates to this method when dealing with a
multiset, but it can also accept any other iterable type.
count
in interface Multiset<E>
element
- the element to count occurrences of
public int add(E element, int occurrences)
occurrences == 1
, this method has the identical effect to Multiset.add(Object)
. This method is functionally equivalent (except in the case
of overflow) to the call addAll(Collections.nCopies(element,
occurrences))
, which would presumably perform much more poorly.
add
in interface Multiset<E>
element
- the element to add occurrences of; may be null only if
explicitly allowed by the implementationoccurrences
- the number of occurrences of the element to add. May be
zero, in which case no change will be made.
public Set<Multiset.Entry<E>> entrySet()
Multiset.Entry
instances, each providing an element of the multiset and
the count of that element. This set contains exactly one entry for each
distinct element in the multiset (thus it always has the same size as the
Multiset.elementSet()
). The order of the elements in the element set is
unspecified.
The entry set is backed by the same data as the multiset, so any change
to either is immediately reflected in the other. However, multiset changes
may or may not be reflected in any Entry
instances already
retrieved from the entry set (this is implementation-dependent).
Furthermore, implementations are not required to support modifications to
the entry set at all, and the Entry
instances themselves don't
even have methods for modification. See the specific implementation class
for more details on how its entry set handles modifications.
Invoking Multiset.Entry.getCount()
on an entry in the returned
set always returns the current count of that element in the multiset, as
opposed to the count at the time the entry was retrieved.
entrySet
in interface Multiset<E>
public void clear()
clear
in interface Collection<E>
public int size()
size
in interface Collection<E>
public int remove(@Nullable Object element, int occurrences)
Multiset
occurrences == 1
, this is functionally equivalent to the call
remove(element)
.
remove
in interface Multiset<E>
element
- the element to conditionally remove occurrences ofoccurrences
- the number of occurrences of the element to remove. May
be zero, in which case no change will be made.
public int setCount(E element, int count)
Multiset
setCount
in interface Multiset<E>
element
- the element to add or remove occurrences of; may be null
only if explicitly allowed by the implementationcount
- the desired count of the element in this multiset
public boolean isEmpty()
isEmpty
in interface Collection<E>
isEmpty
in class AbstractCollection<E>
public boolean contains(@Nullable Object element)
Multiset
This method refines Collection.contains(java.lang.Object)
to further specify that
it may not throw an exception in response to element
being
null or of the wrong type.
contains
in interface Multiset<E>
contains
in interface Collection<E>
contains
in class AbstractCollection<E>
element
- the element to check for
true
if this multiset contains at least one occurrence of
the elementpublic boolean add(@Nullable E element)
Multiset
This method refines Collection.add(E)
, which only ensures
the presence of the element, to further specify that a successful call must
always increment the count of the element, and the overall size of the
collection, by one.
add
in interface Multiset<E>
add
in interface Collection<E>
add
in class AbstractCollection<E>
element
- the element to add one occurrence of; may be null only if
explicitly allowed by the implementation
true
always, since this call is required to modify the
multiset, unlike other Collection
typespublic boolean remove(Object element)
Multiset
This method refines Collection.remove(java.lang.Object)
to further specify that it
may not throw an exception in response to element
being null
or of the wrong type.
remove
in interface Multiset<E>
remove
in interface Collection<E>
remove
in class AbstractCollection<E>
element
- the element to remove one occurrence of
true
if an occurrence was found and removedpublic boolean setCount(E element, int oldCount, int newCount)
Multiset
Multiset.setCount(Object, int)
, provided that the element has the expected
current count. If the current count is not oldCount
, no change is
made.
setCount
in interface Multiset<E>
element
- the element to conditionally set the count of; may be null
only if explicitly allowed by the implementationoldCount
- the expected present count of the element in this multisetnewCount
- the desired count of the element in this multiset
true
if the condition for modification was met. This
implies that the multiset was indeed modified, unless
oldCount == newCount
.public boolean addAll(Collection<? extends E> elementsToAdd)
This implementation is highly efficient when elementsToAdd
is itself a Multiset
.
addAll
in interface Collection<E>
addAll
in class AbstractCollection<E>
public boolean removeAll(Collection<?> elementsToRemove)
Multiset
Note: This method ignores how often any element might appear in
c
, and only cares whether or not an element appears at all.
If you wish to remove one occurrence in this multiset for every occurrence
in c
, see Multisets.removeOccurrences(Multiset, Multiset)
.
This method refines Collection.removeAll(java.util.Collection>)
to further specify that
it may not throw an exception in response to any of elements
being null or of the wrong type.
removeAll
in interface Multiset<E>
removeAll
in interface Collection<E>
removeAll
in class AbstractCollection<E>
public boolean retainAll(Collection<?> elementsToRetain)
Multiset
Note: This method ignores how often any element might appear in
c
, and only cares whether or not an element appears at all.
If you wish to remove one occurrence in this multiset for every occurrence
in c
, see Multisets.retainOccurrences(Multiset, Multiset)
.
This method refines Collection.retainAll(java.util.Collection>)
to further specify that
it may not throw an exception in response to any of elements
being null or of the wrong type.
retainAll
in interface Multiset<E>
retainAll
in interface Collection<E>
retainAll
in class AbstractCollection<E>
Multisets.retainOccurrences(Multiset, Multiset)
public boolean equals(@Nullable Object object)
true
if the given object is also a multiset and contains equal
elements with equal counts, regardless of order.
This implementation returns true
if object
is a multiset
of the same size and if, for each element, the two multisets have the same
count.
equals
in interface Multiset<E>
equals
in interface Collection<E>
equals
in class Object
public int hashCode()
((element == null) ? 0 : element.hashCode()) ^ count(element)
over all distinct elements in the multiset. It follows that a multiset and
its entry set always have the same hash code.
This implementation returns the hash code of Multiset.entrySet()
.
hashCode
in interface Multiset<E>
hashCode
in interface Collection<E>
hashCode
in class Object
public String toString()
It is recommended, though not mandatory, that this method return the
result of invoking Multiset.toString()
on the Multiset.entrySet()
, yielding a
result such as [a x 3, c, d x 2, e]
.
This implementation returns the result of invoking toString
on
Multiset.entrySet()
.
toString
in interface Multiset<E>
toString
in class AbstractCollection<E>
|
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